Session: Thursday Morning, May 16

Time: 9:20

Interface waves often play a significant role in seafloor propagation and
scattering problems. Because they are not solutions to the pure acoustic wave
equations, but require a nonzero shear modulus, they are frequently overlooked
in model and inversion studies. There are two areas in particular where
interface waves are relevant in underwater acoustics: (1) when the source and
receiver are close (in terms of wavelengths) to the seafloor, and (2) when
interface roughness or heterogeneities near the interface act as secondary
scatterers. The first case is important for low-frequency propagation in shallow
water. The second case is important in scattering problems such as low-angle,
monostatic backscatter or the scattered field of seafloor or buried ordinance.
Insight into the generation and propagation mechanisms of interface waves can be
gained through time-domain shapshots of the wavefield and by analysis of time
series record sections. Animations of wavefront propagation in vertical slices
through the seafloor show clearly the energy partitioning between the various
body and interface wave types. [Work supported by ONR.]